JPS60209034A - Composite fiber blend - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for producing fiber tow useful in forming composite products. More particularly, the present invention relates to a method for making fiber tows comprising fiber blends containing strong reinforcing fibers useful in forming composite articles. The invention further relates to such a fiber tow and a method of forming a composite using this fiber tow.

BACKGROUND OF THE INVENTION Fiber reinforced products have been known for some time (e.g. U.S. Pat. No. 3,914,499; 3,969.171; 4,2
14,931 and 4.3'41.835).

It is also known to mix two types of fibers of the same or different types, especially in order to increase bulk (e.g. U.S. Pat. Nos. 4,219,997; 4,218,869; 3.9
59,962; 3.968.638 and 3.958
．． It is further known that the mixing of dissimilar fibers is facilitated by various fluid chefs (e.g., U.S. Pat. Nos. 3,958,310 and 4, supra).
No. 147,020, although in the latter patent the yarn is cut into short lengths after mixing).

US Pat. No. 4,226,079 discloses the combination of 24 different fiber classes to produce bulk yarn. The fibers are mixed in a gent mixing zone. However, the fibers disclosed in this patent are a combination of polyester and polyamide, and there is no disclosure of a combination of strong reinforcing fibers and thermoplastic fibers.

US Pat. No. 3,175,351 discloses a method for bulk processing continuous filament yarns. Although this US patent also discloses that the two types of yarns that are mixed may be of different compositions, none of the fiber compositions disclosed are strong reinforcing fibers as used in the present invention.

U.S. Pat. No. 3,859,158 discloses making carbon fiber reinforced composite products by forming an open carbon fiber fabric and coating it with a carbonaceous material. U.S. Pat. No. 4,368,234 discloses a reinforcing composite fiber formed by alternating strips of graphite fibers and low modulus fibers. However, the fabric disclosed in this patent is subsequently impregnated with a thermosetting resin and cured before use.

U.S. Patent Application No. 368,491 to Buckley et al., assigned to the present applicant, discloses a woven fabric comprising fusible fibers and infusible fibers, the infusible fibers including graphite or carbon fibers. However, an improved woven fabric is disclosed in which the fusible fibers are thermoplastic in nature.

According to this US patent application, fusible fibers and infusible fibers are woven into a fabric and then heated above the melting point of the fusible fibers to thermally bond the fibers together.

However, this U.S. patent application does not disclose the production of a tow product with linearly mixed fibers, or even that this product is useful for forming composite products, nor does it disclose that the product is useful for forming composite products. There is also no disclosure of the use of such means to produce such products.

(Problems to be Solved by the Invention) There are two types of conventional methods for forming fiber-reinforced composites. The first method, which is more ancient, involves applying or coating a tow or woven reinforcing fiber with a solution of thermosetting material and/or a low viscosity melt to form a tape or woven prepreg. This method only requires hardening.

The second method is to extrude a reinforcing fiber tape impregnated with a high melting point thermoplastic polymer. These tapes or fabrics are then used to form composites. but,
Prepregs formed by either of these methods are somewhat difficult to handle. Specifically, conventional thermoplastic tapes are stiff, paperboard-like, and cannot be draped through complex shaped molds. Although heat-cured prepregs were somewhat more flexible, they were often extremely sticky and difficult to handle. As a result, both types of tape have been of limited use.

It is therefore an object of the present invention to produce fibrous blends useful for forming fiber reinforced composites.

Another object of the invention is to produce materials, such as woven fabrics, that can be molded into composites.

The above and other objects can be achieved by the method of the invention described below.

(Means for Solving the Problems) A method for producing a mixed fiber tow according to the present invention comprises forming a fiber tow from a large number of strong filamentary reinforcing materials,
Forming a tow of thermoplastic polymer fibers separately (C)
The process consists of mixing these two types of tow and taking out the mixed tow for use.

Preferably, the filamentary reinforcement is non-thermoplastic. The mixed tow can then be used to form various fiber reinforced composites.

(Operation) The fiber blend produced by the method of the present invention is flexible, easy to handle, and has good drapability, so it can be used to form articles of complex shapes. Furthermore, since two types of fibers are mixed, good wetting of the reinforcing fibers by the thermoplastic fiber material can be obtained by applying appropriate heat and pressure to the mold. Good wetting is achieved to a large extent due to the substantially uniform distribution of thermoplastic fibers and reinforcing fibers within the fiber blend.

In particular, the products of the present invention are particularly useful for applications where small radii of curvature are incorporated into the final product. For example, with conventional tapes, manufacturing articles with 90° bends was often impossible because the tape would crack or deform at the folds. In contrast, the product of the process of the invention is 0.
It can be used with a small radius of curvature of about 0.002 inch (0.05 stiffness).

Thermoplastic polymers that can be used in the practice of this invention include:
Virtually any type of thermoplastic polymer having a relatively high molecular weight may be used; specific examples include polyethylene, polypropylene, polyester, various polyamides, polyimide, polyamideimide, polyetherimide, polysulfone (e.g., polyether sulfone), polyetheretherketone, polybutylene terephthalate, etc. The melting point of the polymer is higher than ambient conditions + +
en +P+11 L &? -k l no l-)
I OC”y F,l L'y+ *,z <itHigher hot water temperatures ensure that excessive sticking and bonding of the spun fibers is prevented before use.In addition to single-component polymer systems, combinations of desired properties can also be used. In some cases it may be advantageous to use mixtures of different thermoplastic polymers.

A particularly important polymer is liquid crystal polymer (LCP). Examples of such polymers include the fully aromatic polyester resins described in the following publications:
etal, + Journal of Applied Polymer Science (J, ^pp1. Polym, Sci
), Volume II, pp19B-202 (1959),
tb+r polyarylate (polyester from aromatic dicarboxylic acid and bisphenol) J G, B
ier, Polymer, vol. 15, p.
p 527-535 (August 1974), (C1r
Aromatic polyester plastic J S, G, Co
ttis, Modern Plastics (Modern P
lastics) + IIP 62-63 (1975
), and (d) "Poly(p-oxybenzoyl): homopolymers for coatings: copolymers for compression and injection molding" J Roger S, 5tors+ et a
Coatings Plast, Preprint
) Volume 34, k 1. pp 194-197 (19
April 1974). You may also refer to the following US patent: No. 3.03
9,994; 3,169,121; 3.321,4
37i 3,553.167; 3.637.595F
3,651,014; 3,723,388; 3,7
59.870; 3.767.621i 3,77B, 4
10; 3,7B7,370; 3,790,528;
3.829,406; 3.890,256; and 3
, No. 975, 487.

Other polyesters include, for example, (a) [Self-reinforced thermoplastic polyester X7G-A J 11. J, J
Ackson Jr., et al. + American Plastics Industry Association, Reinforced Plastics/Composites Subcommittee, No. 30
Proceedings of the Annual Technical Conference (1975), Section 17-L, Il+11-4, (bl Belgian Patent No. 838
, 935 and 828, 936, (C) Dutch Patent No. 7505551, +d+ West German Patent Publication No. 2520819.2520820.2722120.2
834535.2834536 and 2834537, [81 JP-A-50-43223.52-132116
and 53-021293, and (fl U.S. Pat. No. 3,991.083; 4,991,014i 4.
057,597.4,066.620F 4,067.
852; 4.075.262.4.083,829F
4,093,595i 4,112,212.4.1
18,372; 4,130,545; 4,130.
702; 4,146,702.4,153.779.
4,156.070i 4.159.365; 4,1
60,755; 4,161,470; 4,169.
933; 4.1B1,792; 4,183,895
i 4.1B4,996; 4,188,476, 4,
191,681, 4,201,856; 4,219,
461.4,224,433; 4,226.970;
4,230.81?14,232,143i 4,2
38.598; 4,238,600, 4,239,9
13; 4,242,496.4,245.082;
4,245.804; 4.247,514; 4,2
56.624; 4,265,802i 4,267.
289i 4.269,965.4,279,803.
and No. 4,299,756.

Preferred polyesters and copolyesters are those consisting essentially of structural units having repeating groups of the following general formula: (1) -+0-R1-0+ and (II) +OCRt Co+ and/or (II
) +ORs Co+.

In the above formula, the units l and (if present) are present in substantially equimolar amounts, and Rt, Rt and R8 are (l)6
An aromatic carbocyclic monocyclic or fused ring system consisting of member rings (however, the chain extension bonds in this ring system are 1.3- or 1.4-( (preferably in the 1.4-) position and, if bonded on another ring, preferably in parallel and opposite positions)
, and (2) two or more aromatic 6-membered carbocycles have a single bond (
chemical bond) or transS-vinylene group, and the chain extension bond of each ring is 1.3- or 1.4-
(preferably a ring system at the 1,4-) position, a divalent group containing; ) may also be used. Examples of preferred groups (1) are phenylene and naphthylene. Preferred group (2
) is a two-ring system. Preferred groups ill and (2)
A specific example is shown below.

The above ring system has one or more substituents on one or more rings, for example, chloro, bromo, fluoro, or lower alkyl (having 1 to 4 carbon atoms), except for R8, as described below. It also includes those who do. If only one type of unit ■ and one type of unit ■ are used (i.e., when producing a homopolymer), the aromatic ring system of R1 should be unsubstituted to ensure that oriented fibers are obtained. is preferred. In the case of copolymers, the R1 aromatic ring system is also preferably unsubstituted due to thermal or hydrolytic instability and/or cost of the R3 ring-substituted copolymer.

Up to 25 mol %, preferably up to 5 mol %, based on the total amount of units I, II and ■, forming aromatic polymers not falling under those mentioned above but not interfering with the ability of the polymer to form anisotropic melts. Also included are (co)polyesters that are functional units (ie, units in which a chain extension functional group is attached to an aromatic ring). Examples of such units include, but are not limited to: ? The above-mentioned (co)polyester may contain the units ■ and ■ in substantially equimolar amounts, contain only the unit ■, or contain a combination of the units ■, ■, and ■.
Unit of course! , (1) and (2), two or more types of units can be present in the polymer.

Preferred (co)polyesters for use in the present invention are those consisting essentially of units (1) and (2). In such polymers, R+ is 1,4-phenylene, chloro-, dichloro-, bromo-, dibromo-, methyl-, dimethyl-
R8 is selected from the group consisting of
is trans-C4-cyclohexylene, trans-
2+5-dimethyl-1,4-cyclohexylene, tra
ns-vinylene bis(l,4-phenylene"), 4.
4-biphenylene, 2,6-naphthylene, and 1,
Preferably selected from the group consisting of 4-phenylene,
However, two or more types of either units I or H are present. Among such copolyesters, the following two types are particularly preferred in terms of properties and cost. The first type are polymers consisting essentially of the following repeating units: where X is selected from the group consisting of chloro, bromo, fluoro and methyl groups, n is 1 or 2, and Y is 4,
selected from the group consisting of 4'-biphenylene and 2,6-naphthylene, and the ratio of is in the range of 4:1 to 1:4. The second type of polymer is a polymer consisting essentially of the following repeating units: where 2 is selected from the group consisting of 4,4°-biphenylene, 2,6-naphthylene and 1,4-phenylene; The ratio is within the range of 4:1 to 3:2. Both types of polymers may contain up to 25 mole % of units outside the above ranges, as discussed above.

Dicarboxylic acids that can be used include terephthalic acid, 4,
4′-bibenzoic acid, 4,4°-oxydibenzoic acid, 4.
4°-thiodibenzoic acid, 4-carboxyphenoxyacetic acid, C4'-trans-stilbenedicarboxylic acid, 2°6-naphthalene dicarboxylic acid, ethyleneoxy-4,4
"-dibenzoic acid, isophthalic acid, halogen- and methyl-substituted derivatives of the above dicarboxylic acids, C4-tranS-
Examples include cyclohexanedicarboxylic acid, 2,5-dimethyl-1°4-trans-cyclohexanedicarboxylic acid, and the like.

Examples of phenolic carboxylic acids include 6-hydroxy-
2-naphthoic acid, 4-hydroxy-4°-carboxyazobenzene, ferulic acid, 4-hydroxybenzoic acid, 4
-(4'-hydroxyphenoxy)benzoic acid and 4-
hydroxycinnamic acid, as well as alkyls of the above compounds,
Alkoxy and halogen substituted derivatives include,
It is not limited to these.

As the type of (co)polyester containing only the unit ■, preferred are polymers consisting essentially of the following two types of repeating units: A convenient method of preparation, preferably carried out by melt polycondensation with a cycloaliphatic dicarboxylic acid or a derivative thereof, is the melt polycondensation of a diacetate ester of a dihydric phenol with a dicarboxylic acid. Alternatively, phenolic carboxylic acids or derivatives thereof can be used as coreactants in the production of polyesters and copolyesters.

Examples of dihydric phenols preferably used in the form of diacetate derivatives include hydroquinone, chlorohydroquinone, bromohydroquinone, methylhydroquinone, dimethylhydroquinone, dichlorohydroquinone, dibromohydroquinone, 4,4'-oxydiphenol, 4, 4
゛-isopropylidenediphenol, 4.4'-thiodiphenol, 4.4'-biphenol, 3.5.3',
5°-tetramethyl-4,4”-biphenol, 3,5
．． 3',5''-tetrachloro-4,4'-biphenol, 2,6-cyhydroxynaphthalene, 2,7-cyhydroxynaphthalene, and 4,4'-methylene diphenol can be mentioned.

Also, U.S. Patent Nos. 4.112,212; 4.130,
Anisotropic polymers can also be made by polymerizing methylacryloxybenzoic acid using an alkali metal hydroxide and a free radical polymerization initiator, as described in No. 702 and No. 4.160.755. .

Phenolic carvone M derivatives that can be used include p-acetoxybenzoic acid and p-acetoxycinnamic acid.

Examples of various polyesters and copolyesters are listed below, but are not limited to these. (Methyl-1,4-phenylene tranS-hexahydroterephthalate/terephthalate) (8/
2), copoly(chloro-1,4-phenylene/tr
ans-hexahydroterephthalate/isophthathy 1
-) (9/1) and (8/2), copoly (ethyl-1,4-phenylene terephthalate/2,6-naphthalate) (7/3), copoly (tert-butyl-1,4-phenylene /3.3", 5.5'-tetramethyl-4,4'-biphenylene terephthalate)
(7/3), copoly(chloro-1,4-phenylene 3.3', 5.5'-tetrachloro-4,4°-biphenylene terephthalate)) (7/3).

Liquid crystalline polymers, including fully aromatic polyesters and poly(ester-amides), suitable for use in the present invention can be produced by a variety of ester production techniques with functional groups that form the necessary repeating units by condensation. This can be carried out by reacting organic monomer compounds. For example, the functional groups of these organic monomer compounds may be carboxylic acid groups, hydroxyl groups, ester groups, acyloxy groups, acid halides, amine groups, and the like. The above organic monomer compounds can be reacted without the presence of a heat exchange fluid by the melt acidolysis method. In this method, the monomers are first heated together to form a molten liquid of the reactants, and as the reaction continues, the resulting polymer particles become suspended in the liquid. Vacuum may be applied at the final stage of the condensation to facilitate removal of by-product volatiles (eg acetic acid or water).

US Pat. No. 4,083,829 describes a slurry polymerization process that can also be employed to produce wholly aromatic polyesters suitable for use in the present invention. According to this method, a solid product is obtained in suspension in a heat exchange medium. Although the process of this US patent is intended for the production of fully aromatic polyesters, it can also be used to produce poly(ester-amides).

Melt acidolysis method or U.S. Pat. No. 4,083,82
Regardless of which slurry polymerization method No. 9 is employed, the organic super-reactant from which the fully aromatic polyester used in the present invention is derived is in a modified form in which the normal hydroxyl groups of this monomer are esterified (i.e. The lower acyl group preferably has about 2 to 4 carbon atoms, and preferably the acetate ester of the organic monomer reactant is used for the reaction. Poly
(ester-amide), the amine group can also be subjected to the reaction as a lower acylamide.

Melt Acidolysis Method or U.S. Patent No. 4.083.82
Representative catalysts that may optionally be used in any of the No. 9 slurry polymerization methods include dialkyltin oxides (e.g., dibutyltin oxide), diaryltin oxides, titanium dioxide, antimony dioxide, alkoxytitanium silicates, titanium alkoxides, carboxylic acids. alkali and alkaline earth metal salts (eg, zinc acetate), Lewis acids (eg, BFs), gaseous acid catalysts such as hydrogen halides (eg, HCJ), and the like. Generally, the amount of catalyst used is about 0.001 to 1% by weight, most usually about 0.01 to 0.2% by weight, based on the total weight of monomers.

Fully aromatic polyesters and poly(ester-amides) suitable for use in the present invention tend to be substantially insoluble in common polyester solvents and are therefore not amenable to solution processing. However, as already mentioned, such polyesters can be easily processed using common melt processing methods. Particularly preferred wholly aromatic polymers are somewhat soluble in pentafluorophenol.

Preferred wholly aromatic polyesters for use in the present invention are:
Generally about 2,000 to 200,000, preferably about 10,000 to 5,000, more preferably about 2
It exhibits a weight average molecular weight of 0.000 to 25.000. Preferred wholly aromatic poly(ester-
amide) generally about s, ooo to 50,000, preferably about 10,000 to 30,000, for example about 15
,000 to 17,000. Such molecular weight measurements can be performed by gel permeation chromatography or other standard measurements that do not involve solution formation of the polymer, such as end group measurements by infrared spectroscopy on compression molded films. Moreover, the molecular weight can also be measured using a light scattering method in the state of a pentafluorophenol solution.

The fully aromatic polyesters and poly(ester-amides) used in the present invention generally have a concentration of at least about 2.0 a/g when dissolved in pentafluorophenol at 60<0>C, e.g. 2.0～
It exhibits a logarithmic viscosity number (1, V,) of 10.0 dl/g.

For purposes of the present invention, the aromatic rings present in the polymer backbone of the polymer component may be those in which at least some of the hydrogen atoms bonded to the aromatic rings have been replaced. Such substituents include alkyl groups having up to 4 carbon atoms, alkoxy groups having up to 4 carbon atoms, halogen, and other aromatic rings such as phenyl and substituted phenyl groups. Preferred halogens include fluorine, chlorine and bromine. Although bromine atoms tend to dissociate from organic compounds at high temperatures, bromine is more stable attached to aromatic rings than to aliphatic chains, making it inconvenient to include as a possible substituent for aromatic rings. There isn't.

A key feature of the present invention, intended for a substantially uniform distribution of blended fibers, is the combination of a compatible thermoplastic material with a non-thermoplastic material having a sufficiently high melting temperature, thereby making the thermoplastic Effective bonding and integration can be achieved by applying sufficient heat and pressure to melt the materials, but not the reinforcing material. Therefore, the use of relatively high melting point thermoplastic materials is also encompassed by the reinforcing fibers of the present invention. However, in the specification, such materials are referred to as "non-thermoplastic" for the sake of simplicity.
It states:

The reinforcing fibers that can be used in the present invention are metallic or ceramic, amorphous, polycrystalline or single crystal reinforcing fibers or filaments.

Common examples include carbon, glass, boron and boron nitride, ceramic fibers such as silicon carbide, silicon nitride and alumina, aramids, ordered polymers, etc.

The use of carbon fibers as reinforcing fibers is described in U.S. Patent Application Nos. 589,823, 589,825 and 589,
No. 817 (both filed on March 15, 1984).

Glass fibers that can be used are industrially produced and commercially available. Glass fiber is produced by drawing molten glass at high speed from a molten glass contained in a platinum container with a large number of very fine holes in the bottom, and turning the glass into fibers with extremely fine diameters. Immediately after the glass filaments are drawn from the platinum container, commonly called a "bush", they are pretreated with a sizing agent which serves to improve the compatibility of the final glass yarn with the thermoplastic fiber used.

Glass fibers that can be used in the present invention include non-stranded filamentary continuous glass fibers, stranded glass filaments, and straight bundles of stranded glass filaments (including twistless rovings);
In this specification, all of the above are referred to as glass fibers.

Sizes contemplated by this invention and suitable for use in its practice are those conventionally used in the treatment of glass fibers.

Such sizing agents contain as an essential component a glass fiber adhesion agent such as an organosilicon compound or a unirna complex compound.

Preferred fixing agents are aminosilanes such as γ-aminopropyltriethoxysilane, N-(β-aminoethyl)-r-aminopropyltriethoxysilane. However, any other organic silanes and corresponding silanols and polysiloxanes can also be used. Representative examples of other suitable adhesion promoters that can be used in the practice of this invention include organosilicon compounds, their hydrolysis products and polymerization products (polysiloxanes).

Instead of the above-mentioned organosilicon compound, a unirna complex compound in which a carboxylad group is coordinated to the core atom of trivalent chromium can also be used, and this carboxylad group may further contain an amino group or an epoxy group. Suitable unirna-complex compounds include stearade dichrome chloride, methacrylad dichrome chloride, aminopropylad dichrome chloride, glycine dichrome complex or gliclad dichrome chloride.

Ceramic fibers that can be used in the present invention include silicon carbide fibers (ultrafine β-5iC crystals), silicon nitride fibers (SisNJ
and alumina fiber (^1.o).

Although any silicon carbide fiber system having the required strength can be used, multifilament silicon carbide yarns having an average filament diameter of up to 50 microns are preferred, especially yarns having an average filament diameter of 5 to 15 microns.

If a silicon carbide monofilament is used, a typical silicon carbide monofilament having a diameter of about 140 microns is commercially available from AVCO Systems, Inc., USA. This fiber exhibits an average tensile strength of up to 3450 MPa and 13
It has a heat resistance ability of 00°C or higher and is stable in oxidizing environments.

Alumina fibers have been commercially available for some time. It has been of particular interest for applications in metal matrix composites due to its excellent strength and modulus (especially at high temperatures). In the past, alumina fibers were divided into two main types: large-diameter (>350μ) single-crystal fibers and alumina whiskers.
. Single-crystal fibers are very expensive, and whiskers have problems in handling and processability, so enthusiasm for using them in composite materials has waned. However, the situation has changed with the advent of high-quality alumina yarns, which are being seriously considered for use in composites due to their potential low cost and promising mechanical properties. Generally, such alumina fibers are manufactured by DuPont and 3M in the United States, and Sumitomo Chemical.

DuPont's alumina fiber, called FP woven fiber, has a cross section with a diameter of 20. It is a long (continuous length) yarn having a circular shape of 210 fibers per tow.

This takes two forms. Type 2 is made of pure α-alumina, and type 2 is similar, but covered with a thin layer of glass. Originally, the ■ type was for resin matrix composites, and the ■ type was for metal matrix composites. However, both types of alumina fibers have been found suitable for ceramic composites in the present invention. The initial fiber strength is about 1380 MPa (200,000 psi), which is not particularly high, but this strength is stable and unaffected by handling. This is a point that is significantly different from the behavior of strength properties exhibited by composites reinforced with .

Alumina fibers manufactured by Sumitomo Chemical are also produced in the form of yarns, but there are some areas in which they are not similar to FP woven fibers. In fact, this fiber is not pure alumina, contains a small amount of Sing, and has a very fine structure, so it is said that it can be used at temperatures as high as 1350°C.

This fiber is promising due to its specific mechanical properties. Its specific strength is nearly twice that of FP woven fibers due to its low density and high tensile strength, and its specific modulus is almost the same as the FP woven fiber properties. This alumina fiber produced by Juju Kagaku seems to have excellent handling properties.

Boron nitride has known properties such as extremely high temperature resistance (980°C (1800″F) in an oxidizing atmosphere, 2760°C (5000°F) in a reducing atmosphere), dielectric strength (950V/5IT), wide Due to the high surface and volume resistivities and low dielectric loss tangents in the temperature range, their potential as high temperature reinforcing fibers is very promising.

These fibers are available in various diameters, but preferably have a diameter of about 10 microns, and fibers with a diameter of up to about 30 microns can be used. Continuous boron nitride fibers (boron nitride content 99+χ) are commercially available from Carporundum, Inc., USA.

Reinforcing fibers particularly useful in the present invention are those with a bundle or tow denier of 1 to 100,000 and a filament count of 300 to 300,000, preferably a denier of i, ooo~16,000, and the number of filaments is 3,000~24,000.

The reinforcing fibers also have at least about 100,000 ps
i (7°000 kg/d) and a tensile strength of about 10 to 12
0X10' psi (7~5txios kg/cd)
It is preferable to have a tensile modulus of elasticity of .

Thermoplastic fibers particularly useful in the present invention are those whose bundle cross-sectional area is about 2 to 172 times the bundle cross-sectional area of the reinforcing fiber tow. The denier of a bundle or tow of thermoplastic fibers may range from 1 to 50, and the number of fibers may vary depending on the denier of the single filament (lower denier filaments require a higher number of fibers). , but generally about 10 to 150,000, preferably 10
0 to io, ooo filaments are used. The modulus of the fiber is approximately 50.000 to 500.000 ps
i (3,500 to 35,000 kg/csl). Furthermore, the melting point of thermoplastic fibers is higher than room temperature.
The temperature must be above 0°C, preferably above 135°C. Of course, to be useful in the present invention, the fibers must be below about 1000°F (538°C), preferably 8
It must be able to melt and fuse at temperatures below 00'F (427°C).

The weight mixing ratio of the two types of fibers can vary over a wide range.

However, to produce a satisfactory composite, it is necessary to use a sufficient amount of thermoplastic polymer fibers to completely wet the reinforcing fibers. Generally, greater than or equal to about 30% by volume thermoplastic polymer fibers are used. The upper limit for the amount of thermoplastic polymer fiber used will vary depending on the strength properties desired. Generally, when the amount of reinforcing fibers is less than about 10% by volume, the strength and stiffness properties of the resulting composite product become inferior compared to products containing higher amounts of reinforcing fibers, and It shows little or no improvement compared to the matrix. Preferably, about 20-60% by volume of reinforcing fiber material is present in the mixed tow, and in addition to the reinforcing fibers and thermoplastic fibers used in the present invention, carbon fibers are added as reinforcing fibers to the fiber blends of the present invention. You can also do that. When this additional carbon fiber is added, the amount of reinforcing fiber used can be reduced to about 10% by volume. However, the maximum value of the total amount of the added carbon fiber and the amount of reinforcing I41i miscellaneous used should not exceed the upper limit in the case of the reinforcing fiber alone.

The present invention will now be described in detail with reference to the accompanying drawings.

In FIG. 1, a reinforcing fiber tow 1 having the above characteristics is used.Fibers from a zero reinforcing fiber tow are passed through a fiber guide 3 and a first godet roll 4. 1st
The rotation speeds of the godet roll and the second godet roll 11 are adjusted so that the second godet roll rotates slightly slower than the first godet roll. Therefore, the fibers between these two godet rolls (during which the widening and mixing are carried out by the method of the invention) are in a low tension state 1! (nearly tension-free), which allows effective mixing of the fibers. Each individual thermoplastic polymer fiber, such as a polybutylene terephthalate fiber, is mounted on a bobbin rack 2, and each polymer fiber passes through a fiber guide 3 to a first
Sent to Godeftroll 4. A tension comb (not shown) may be used while the fibers exit the bobbin and before contacting the godet roll. This tension comb improves the contact between the fibers and the godetstrol,
It acts to widen the width of the fiber tow.

At this point in the process of the present invention, neither the reinforcing fibers nor the thermoplastic fibers are mixed or in contact.

Rather, they are wound separately and separately around the first godet roll 4 to provide tension control. After leaving this godet roll, the individual fibers pass separately through a fiber guide 5 to maintain directional control. After passing the fiber guide 5, the thermoplastic polymer fibers pass through a fiber comb 6. The fiber comb has a number of spaced fingers (teeth) that serve to keep the individual fine yarns of thermoplastic polymer fibers separate and spaced apart. On the other hand, after passing through the fiber guide 5, the reinforcing fibers are sent to a gas banding jet 7.

Gas banding jets, shown in Figures 3 and 4, are used to uniformly spread the width of the fiber tow.

Gas "banding" jets also work because the gas jet acts to evenly mix the two types of fiber tows.
It can also be used as a mixing means. The banding jet consists of a gas box 40 into which compressed air or other gas is supplied by conventional adjustable gas metering means 41. The preferred pressure of the gas stream producing the gas jet is about 0.5 to 10 psi (0.035 to 0.7
kg/ai). One or more gas outlets 44 are provided such that gas from within the gas box impinges generally perpendicularly on the fiber tow traveling across the outlets. Preferably, the outlet is V as shown.
It is shaped like a letter V, and the direction of the tip of the V-shape is made to match the direction in which the fiber tow crosses the gas box.

As shown in FIG. 4, the gas banding jet is provided with shims 46 or other means to allow a gas box cover 48 to be attached.
A flow path for the fibers to pass through is ensured.

The gas box cover is held in place by suitable attachment means such as clamps 49.

In another method, shown in FIG. 2, both the thermoplastic polymer fibers and reinforcing fibers are treated with gas banding jet devices 26 and 27, respectively.

However, a fiber comb with multiple spaced fingers as described above may be used in place of the banding jet, especially for polymers with lower molecular weights and lower melting points, such as polybutylene terephthalate.

After both fibers are widened by using two banding jets or a combination of banding jets and a comb, they are mixed by the mixing means 8. In Figure 1,
The mixing means 8 are a pair of fixed rods or bars. Both the fibers from the widened reinforcing fiber tow and the fibers from the widened thermoplastic fiber tow or yarn first come into contact together at the bottom of the first anchoring rond or bar. These fibers then contact the upper surface of a second fixed rond or bar and are subjected to deflection, resulting in mixing. To ensure thorough mixing, both fibers must be spread evenly over their entire width and the spread widths of both fibers must be substantially the same.

Also, the mixing must be done under relatively tension-free conditions.

If high tension is applied to one side of the fiber tow, complete (
or optimal) mixing may not occur. After passing under and over the two fixed bars, the mixed fiber tow may be further mixed using the entangling air jets described above.

After mixing, the fibers are provided with a comb 9 to maintain dimensional stability and a twist guide l to give the mixed fibers a slight twist.
Pass through O. The twist is applied to maintain the mixed state of the fibers. Instead of using true semi-curling, the fibers may be pre-curled by methods well known in the art. Alternatively, a fiber wrapping process may be used to hold the mixed fibers together. The overwrap process can be performed with any suitable type of fiber.

However, it is preferable that the overwrapping fibers consist of a relatively small amount of thermoplastic fibers.

The mixed fibers then pass around the second godet roll 11 once. As mentioned above, this godets troll is the first
In conjunction with godetstrol, it acts to form a relatively tension-free zone to allow for fiber mixing. The fibers are then taken off by take-off rolls 12 for storage. Of course, it is also possible to provide a temporary twist or a true twist before and after this godet roll, or to wrap the fiber tow with another fiber.

In addition, suitable fiber finishing treatments to help hold the mixed fibers together and facilitate handling in subsequent operations;
For example, weaving may be applied to stabilize the blended fibers.

The method shown in FIG. 2 is similar to that in FIG. 1, but is particularly preferred when liquid crystal polymers or other high melting point polymers are used.

In FIG. 2, a roll 21 of reinforcing filament material feeds reinforcing fibers through a tension comb 22 onto a godet roll 25. In FIG. The liquid crystal polymer fibers supplied from the roll 23 pass through a guide 24 and are sent to the same godet roll 25. Separation between both fibers is maintained on this godet roll. As mentioned above, the first godet roll 25, when used in combination with the optional second godet roll 35, serves to maintain the fibers in a relatively tension-free state during the mixing operation. High tension during mixing operations must be avoided to ensure complete mixing.

After the reinforcing fibers and the liquid crystal polymer fibers have passed the first godet roll, they are passed through guides 28 and 29, respectively, to separate gas banding jets 26 and 27. In the gas banding jet, the fibers are spread to a uniform width.The fibers then pass through a second pair of fiber guides 30 and 31 and are mixed using an elongated stationary bar shown at 32. Generally, mixing occurs by feeding the thermoplastic fiber bundle to the same section on the same bar as the reinforcing fibers. At this point in the operation, both tows are the same width and if they contact the same part of the bar at the same time, intimate mixing will occur. Another method of mixing involves feeding two types of fiber tows simultaneously into a single gas jet or other gas mixing device under relatively tension-free conditions.

Alternatively, the fibers may be mixed on a stationary bar and then sent to a gas jet device for further mixing of the fibers.

In the gas mixing means, an air jet impinges on the fibers, preferably perpendicular to the direction of fiber travel.

After mixing, the fibers are passed through a twist guide 33 which adds at least a half twist per yard (0.91 m) to the fibers to ensure dimensional stability. The fibers then pass through a guide 34 and a second godet roll 35, from which they are fed to a take-up roll 36 and wound up.

A method of using the mixed fiber tow of the present invention will now be described. The mixed fiber tow may be in the form of filament wraps or other aggregates, which are placed on a mold and heated under pressure to the flow temperature of the thermoplastic polymer in the tow to provide high strength, high stiffness and light weight. A composite product is formed that is useful for a variety of applications. For example, composites formed from products produced by the method of the invention can be used to form structural parts for spacecraft, aircraft, or automobiles. Further, the reinforcing fiber blend of the present invention can be particularly advantageously used for applications with complex three-dimensional shapes. As previously mentioned, the compositions of the present invention are particularly useful in applications where substantial bending and shaping is required at small radii of curvature. The only limiting factor in forming reinforcing fiber shaped articles using the compositions of the present invention is the "bendability" of the reinforcing fibers themselves. Therefore, using the compositions of the present invention, the minimum radius of curvature is approximately 0.0
About 0.02 inches (0.05ms+), preferably 0.0
Products with a radius of curvature as small as 0.03 inch (0°08 m5+) can be manufactured. In contrast, traditional thermoplastic tapes have a minimum radius of curvature of approximately 0.005 inches (
0.13 m+w) (even if the orientation of the fibers, ie the alignment in one direction, is distorted after tape manufacture). When the structural element formed from the fiber tow of the present invention is heated under pressure to a temperature higher than the melting point of the thermoplastic fibers used, the fibers melt and fuse the reinforcing fibers together, thereby ensuring sufficient dispersion of the reinforcing fibers. A rigid composite product is formed containing the following conditions.

The fiber blends of the present invention can be used to make athletic or recreational equipment such as tennis frames, racquetball frames, hockey sticks, ski poles, fishing rods, golf club shafts, and the like.

The fibers of the present invention are particularly useful in filament winding applications. As mentioned above, in the prior art, it has been very difficult to manufacture composite articles using conventional fibrous tapes. Conventional tapes, which are manufactured on a very large scale, are difficult to handle in small quantities and are particularly difficult to form into articles of complex shapes. Conventional tapes have been used in the filament winding method with good results, but when it is desired to produce long and thin tapes, the filament winding method is recommended when reinforcing fibers are used in combination with a thermosetting resin. It was limited. Conventional methods have either applied a thermosetting coating to the reinforcing fibers and then wrapped them around a mold, or the reinforcing fibers have been wrapped into filaments and then coated with a thermosetting material. However, as a result, it has often been difficult to achieve actual penetration of the thermoset material and/or good wetting of the tightly wound product by the thermoset material.

When the method of the present invention is applied to an improved filament winding method,
The combination of fiber reinforcement and thermoplastic polymer can be used to produce products with complex shapes when the fiber blend is oriented in a direction that is not parallel to the long axis of the product. This improved filament winding process originates from the use of the mixed tow of the present invention. The tow of the present invention can be fed directly to a filament winder. As the filament winder moves around or above and below the mandrel or former, one of the reinforcing fibers/thermoplastic fibers hits the mold directly and immediately melts and fuses the thermoplastic polymer fibers within the reinforcing fiber tow. Heated by radiant heaters or other suitable heating means. In other words, the reinforcing fiber/thermoplastic fiber tow should be subjected to heating under pressure immediately or preferably as soon as it contacts the mandrel. After complete melting and resolidification has occurred, the mandrel should be properly heated. the mandrel may actually become part of the product.

Another unique use for the fiber blends produced by the present invention is in processes involving the formation of woven fabrics by standard methods.

According to this method, the tow of the present invention is used alone or in combination with other tows or fibers to form a woven mat. The woven fabric produced by the method of the invention is applied to the desired mold or other device used to form the composite.

The conventional method utilized to form such materials is to sequentially deposit a layer of reinforcing fibers (eg, glass fibers), followed by a layer of thermoplastic film, then another layer of glass fibers, and so on. On the other hand, the method described above allows the material to remain bonded in the form of a uniform woven fabric, which is much easier to apply in a mold. After the composite is shaped, heating under pressure to a temperature above the flow A degree of the thermoplastic polymer used results in a composite with good mechanical strength and stiffness. This increase in strength and stiffness can be achieved by moving the reinforcing fibers in one or more directions, i.e., by moving the reinforcing fibers into a defined vector (def
ining vector),
can be caused to occur.

A tow of liquid crystal polymer fibers is obtained using a copolymer prepared from 6-hydroxy-2-naphthoic acid and p-hydroxybenzoic acid as a base material. This liquid crystal polymer has a density of 1.4
g/cc, and the tow itself is formed from 660 filaments (2.25 denier/filament), and the initial modulus of this tow is 5670 g.

The strength is 10.5 g/d and the elongation is 2%. The other fiber used to mix with the liquid crystal polymer fiber was
E-glass fiber (204 filaments labeled ECG 150 Ilo), the density of this reinforcing glass fiber is 2.55g/cc, and the tensile strength is 300X10
"ps+(21xlO"kg/cd), tensile modulus is 10.5x10'ps+(0,74xlO'kg
/d), the final elongation is 2.8%.

This glass fiber is commercially available from PPG Industries and OCF.

The bobbin around which the liquid crystal polymer fiber tow is wound and the bobbin around which the glass fiber tow is wound are arranged on a bobbin rack so as to be spaced apart from each other. The fibers from both bobbins are fed into one godet roll with the two separated such that after mixing the mixed tow contains about 50% liquid crystal polymer and about 50% glass fibers by volume. -
Let it spin.

The liquid crystal polymer fibers are preloaded with a 50 g load using a tensioning device before being rotated around the godet rolls in order to maintain smooth rotation on the godet rolls. After exiting the Godetstrol, both fibers are treated separately with air jet banding. This treatment is carried out using an air jet that impinges air approximately perpendicularly onto the fibers from a V-shaped nozzle. The jet for liquid crystal polymer is 5 psi (0,35 kg/
cd) and the jet for glass fibers is 4 psi (0,
28kg/cd).

After exiting these banding jet devices, the fibers are brought into contact together on the upper and lower sides of two elongated fixed bars arranged parallel to each other, offset up and down, and then passed through fiber guides to the entangling jet device. send. This entangling jet device is of a similar design to the gas banding jet device used earlier. psi(0,5
It operates at a gas pressure of 1 kg/csi). After intimate mixing of the two tows, the fibers are wound onto take-up rolls at a take-up speed of 7-8 m/sin.

A composite test panel (3.5 x 10 inches - 8.9 x 25 cn) is prepared using 20 layers of the resulting mixed fiber tow. To prepare each layer, first place Kapt on a heated drum.
on (trade name) film and then filament winding the fiber blend obtained above in parallel rows onto a drum wrapped with Kapton film.

After that, cover the drum with one sheet of Kapton film,
The entire wrapped drum is heated to temporarily fuse the fibers. The composite containing the 20 fused layers is placed in a pressure mold and heated to about 315°C and held at this temperature for 5 minutes without significant mold pressure. The mold pressure is then increased to 500 psi (35 kg/cd) and maintained at a temperature of about 315° C. for 30 minutes. The material is then cooled to 70° C. and removed from the mold, the resulting material contains 50% by volume E-glass fibers and has a panel thickness of 0.103 inches (2.62 mm).
It is.

Using the same method, a 6-layer 3.5 x 10 inch (
A 8.5 x 25 cm) composite panel is prepared (approximately 60% glass fiber content by volume, panel thickness approximately 0.035 inches = 0.89B). The resulting composite is tested for tensile, flexural and compressive properties with good results.

The same glass fiber used in main example 1 was used, and the tip application amount was approximately 5.
0% by volume polybutylene terephthalate (PBT) /
Prepare a glass fiber blend. The polybutylene terephthalate material used has a density of 1.34 g/cc and a denier of 1520 g/9000 m. This polybutylene terephthalate has a draw ratio of 2.25-1, an initial modulus of 24 g, a tenacity of 5.3 g/d, an elongation of 28%, a melting point of 227 DEG C., and a denier per filament of 2.7. 1 of 33 filament yarns
0 packages are used per creel and all packages are combined into one polybutylene terephthalate fiber tow and sent to 5) lJ Godetstrol. Into this same godet tray, 10 pancages of glass fibers (type 1ICK752) with 408 filaments are fed at intervals such that after mixing a glass fiber/PBT fiber blend of approximately 50:150 in volume is obtained. .

After exiting the Godettrol, the polybutylene terephthalate tow is passed through a fiber comb with about 30 teeth and the glass fiber tow is passed through a fiber comb with about 2.5 to 3 teeth as described in Example 1.
．． Pass through a gas banding jet operating at a pressure of 5 psi (0.18-0.25 kg/c+a). The two types of tow are then mixed by feeding both tows into the same part of the rono above and below the rono which are arranged in parallel. 2.5-3.5
A second gas banding jet of the type described in Example 1 operating at psi (Q, 18-0.25 kg/cj) is used to further aid mixing. After exiting the banding jet, the fibers are passed through a second fiber comb, which is arranged parallel to the direction of fiber passage to form a tensioning path to promote mixing. After that, pass the fiber through the twist guide,
1 yard (0.91m) to maintain the mixed state of the fibers.
) Gives almost half a twist to each hit. The fibers are then
After circling around the godets troll, 7-8 m/
Wind it up at the same speed. To minimize tension during the mixing operation, the second godet roll is rotated at a slightly slower speed than the first godet roll.

In substantially the same manner as described in Example 1, 3.5×10
An inch (8.5 x 25 cm) panel composite was prepared and tested and shows good results.

A sample of the PBT/glass fiber blend prepared above was wrapped with 90 denier polybutylene terephthalate yarn at 4 turns per inch (2,54 cm) as described above to make it suitable for weaving. form a dense yarn. PBT was used as the wrapping fiber because it becomes part of the matrix after the composite is fabricated. The resulting wrapped yarn was then divided into 96 separate yarn pieces and wound onto a spool mounted on a special Draper reel.
XD (product name) - Width 6 inches (15,2
Weave the fabric of c) in a plain weave pattern. The number of stitches of the resulting woven fabric is 1 warp per inch (2,54c+w)
6 threads x 15 weft threads, weight approximately 0.05 oz/y
d” (1,7 g/J), the thickness of this woven fabric is approximately 1
0 mil (0.25 vw), is flexible and dense, and exhibits good dimensional stability. Satisfactory fiber composites with irregular shapes are produced from the resulting woven fabric.

EXAMPLE 1 A fiber blend of about 50150% by volume is prepared using the glass fibers and polyetheretherketone (1'l!IIK) based thermoplastic polymer described in Main Example 1.

Fibers prepared from PEEK have a density of 1.3 g/cc
, melting point is 338℃, initial modulus is 53 kura, strength is 2
°7 g/d, elongation of 65%, supplied in tows of 10 filaments per puff cage, each filament having a denier of 361 g per filament.
/9000 m. Four tows (10 filaments per package) are creeled and the fibers are mixed together in one godet roll. However, it was kept at a distance from the glass fibers wound around this godet roll. The PEEK fibers are then passed through a fiber comb as described in Example 2 before being passed through a gas
Send to banding jie nodo. The glass fibers that have come out of Godetstrol are also introduced into another gas banding die.

Both sheets are approximately 3psi (0.21kg/aJ)
Operate with pressure. Both fibers coming out of the die nodo are mixed on the upper and lower sides of the two 1,4-te arrangement, and passed through a second parallel fiber comb to maintain dimensional stability. After that, the second bode nodrol is passed around and wound at a speed of 7 to 10+w/a+in.A satisfactory composition is obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing various apparatuses that may be used for carrying out the method of the invention; FIG. 3 is a perspective view of a gas widening device that may be used to carry out a portion of the method of the invention, and FIG. 4 is a perspective view of the same device as in FIG. 3 with the top plate removed. , 217 reinforcing fiber tow 4, 11.25.35: Godetstrol 1, 26.2
'7: Gas banding jet 8, 12: Fixed port for mixing, throat 9, 12: Fiber comb lO; Twist guide 12, 36: Take-up roll 40: Gas box 44: Gas discharge port Applicant Celanese Corporation Agent Person Patent Attorney Akira Hirose - D 01 F 6/62 6791- 6/84 6791-

Claims (33)

[Claims] (1) Spun fibers of a thermoplastic polymer with a melting point of about 50° C. or higher of about 90-30% by volume based on total fiber content and about 10-70% by volume based on total fiber content for non-thermoplastic reinforcement Continuous fiber tow useful for forming composite products, consisting of an intimate blend of fibers. (2) spun fibers of a thermoplastic polymer with a melting point of about 50° C. or higher of about 90-30% by volume based on total fiber content and about 10-70% by volume based on total fiber content for non-thermoplastic reinforcement; Continuous fiber tow useful for forming composite products consisting of an intimate blend of fibers, the tow having a minimum of 0.00
The continuous fiber tow according to claim 1, which can be formed into a product with a radius of curvature of 2 inches (0.05 mm). (3) Thermoplastic polymer fiber content is approximately 80-40%
The quick-reading fiber tow according to claim 1 or 2, wherein the reinforcing fiber content is about 20 to 60%. (4) The reinforcing fiber is made of a material selected from the group consisting of metal, ceramic, amorphous, polycrystalline, and single crystal fiber. Continuous fiber tow. (5) The continuous fiber tow according to claim 4, wherein the reinforcing fibers are made of glass, boron, aramid or ceramic fibers. (6) The thermoplastic polymer fiber is polyethylene, polypropylene, polyester, nylon, polyamideimide,
The continuous fiber tow according to claim 1 or 2, which is a fiber of a polymer selected from the group consisting of polyetherimide, polyether sulfone, polyether ether ketone, and wholly aromatic polyester resin. (7) The continuous fiber tow according to claim 1 or 2, wherein the thermoplastic polymer is a liquid crystal polymer. (8) The continuous fiber tow according to claim 1 or 2, wherein the thermoplastic polymer is a wholly aromatic polyester. (9) A method for producing a fiber tow useful for forming composite products, comprising: forming a tow of (al non-thermoplastic reinforcing fibers), (bl consisting of spun fibers of a thermoplastic polymer having a melting point of about 50° C. or higher; Forming a continuous tow, (C1 mixing the non-thermoplastic reinforcing fiber tow and the thermoplastic polymer fiber tow, +d) taking out the mixed fiber tow, tan) Two manufacturing methods. (10) forming a tow of (al non-thermoplastic reinforcing fibers);
(bl) Form a continuous tow consisting of spun fibers of a thermoplastic polymer having a melting point of about 50°C or higher, and mix the ICI non-thermoplastic reinforcing fiber tow and the thermoplastic polymer fiber tow using a gas mixing means. , +dl mixed fiber tow is taken out. 10. A method for producing a fiber tow useful for forming a composite product according to claim 9. (11) Claim 9 or 1, wherein the reinforcing fiber is made of a material selected from the group consisting of metal, ceramic, amorphous, polycrystalline, and single crystal fiber.
The method described in Section O. (12) The method according to claim 11, wherein the reinforcing fibers are made of glass, boron, aramid or ceramic fibers. (13) The thermoplastic polymer fiber is a polymer fiber selected from the group consisting of polyethylene, polypropylene, polyester, nylon, polyamideimide, polyetherimide, polyethersulfone, polyetheretherketone, and wholly aromatic polyester resin. A method according to claim 9 or 10. (14) The method according to claim 9 or 10, wherein the thermoplastic polymer is a liquid crystal polymer. (15) The method according to claim 9 or 1θ, wherein the thermoplastic polymer is a wholly aromatic polyester. 16. The method of claim 1O, wherein the gas mixing means comprises a gas box with gas impingement means for delivering a gas flow generally perpendicular to the fibers. (17) A patent in which the mixing means is an elongated rono, and the reinforcing fiber tow and the thermoplastic polymer fiber tow are mixed by simultaneously contacting the same portion of the rono in a relatively tension-free state. The method according to claim 9. (18) Claim 1 which uses one more ronodo
The method described in Section 7. (19) The method according to claim 9, 1θ, or 16, in which the mixing step is performed with the fibers in a relatively tension-free state. (20) The method according to claim 9 or 10, wherein the mixed tow contains about 10 to 70% by volume of reinforcing fibers. (21) The method of claim 9 or 10, wherein the mixed tow contains about 20-60% by volume of reinforcing fibers. (22) the blended tow contains about 10-70% by volume reinforcing fibers selected from the group consisting of glass, boron, and ceramic fibers, and thermoplastic polymer fibers a! -u
++ w <1 -no -ull it'I し4-necked noso ze l -Dingsu 卆J-ray Consisting of nylon, polyamideimide, polyetherimide, polyether sulfone, polyether ether ketone, and wholly aromatic polyester resin. The method according to claim 9 or 1θ, wherein the fibers are of a polymer selected from the group consisting of: (23) for spun fibers of thermoplastic polymers with a melting point of about 50° C. or higher of about 90-30% by volume based on total fiber content and about 10-70% by volume based on total fiber content for non-thermoplastic reinforcement; A method of forming a composite article comprising contacting an intimately mixed continuous fiber tow containing a mixture of fibers with a mold and heating the tow above the melting point of the thermoplastic polymer fibers. (24) The method according to claim 23, wherein the reinforcing fibers are formed from a material selected from the group consisting of metal, ceramic, amorphous, polycrystalline, and single crystal fibers. (25) The method according to claim 24, wherein the reinforcing fibers are formed from glass, boron, aramid or ceramic fibers. (26) The thermoplastic polymer fiber is a polymer selected from the group consisting of polyethylene, polypropylene, polyester, nylon, polyamideimide, polyetherimide, polyether sulfone, polyether ether, and wholly aromatic polyester resin. 24. The method of claim 23, wherein the fiber is a fiber. (27) The method according to claim 23, wherein the thermoplastic polymer is a liquid crystal polymer. (28) The method according to claim 23, wherein the thermoplastic polymer is a wholly aromatic polyester. (29) Claim 23, wherein the intimately mixed tow contains about 20-60% by volume of non-thermoplastic reinforcing fibers.
The method described in section. 30. The method of claim 23, wherein the tow of intimately mixed fibers is applied to the mold by filament winding. (31) The method according to claim 23, wherein the tow of fibers is applied to the mold in the form of a woven fabric. (32) The method according to claim 24, wherein the composite product is an exercise or recreational product. (33) The method according to claim 32, wherein the composite product is a tennis racket frame.